The Rotational Spectrum of Perfluoropropionic Acid

The pure rotational spectrum of perfluoropropionic acid, CF 3CF 2COOH, has been studied by a pulsed nozzle, chirped-pulse Fourier transform microwave spectrometer in the frequency range of 8-14 GHz. a total of 81 transitions, including a-type, b-type, and c-type transitions have been observed and analyzed. the rotational constants and the five quartic centrifugal distortion constants were determined for the first time. the rotational constants are a = 1893.5299(4) MHz, B = 1175.7031(4) MHz, and C = 1118.2017(5) MHz. Quantum chemical calculations and the spectral analysis indicate that the observed conformer is the gauche form of perfluoropropionic acid with calculated dihedral angles ∠CCCO = 106° and 107° from MP2/6-311G++(3df, 3pd) and MP2/Aug-CC-pVDZ calculations, respectively. the experimental spectroscopic constants are compared to those obtained from ab initio calculations